double back vs reenter

double back

verb
  • To retrace one's steps; to go back where one has already gone. 

reenter

verb
  • To enter again; return into. 

  • To enter again; retype, reinput. 

  • To cut deeper where the aqua fortis has not bitten sufficiently. 

How often have the words double back and reenter occurred in a corpus of books? (source: Google Ngram Viewer )